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                [USACO2011 Open] Learning Languages                </h1>
                <p>时间限制：5s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：128MB</p>			</div>
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                                <h3>题目描述</h3><p><p><font size="3" face="Times New Roman"><span style="display: none" id="1380426866143S">&nbsp;</span><br />
农夫约翰的N（2 &lt;= N&lt;=10,000）头奶牛，编号为1.. N，一共会流利地使用M（1&lt;= M &lt;=30,000）种语言，编号从1 .. M.，第i头，会说K_i（1 &lt;= K_i&lt;= M）种语言，即L_i1, L_i2,..., L_{iK_i} (1 &lt;= L_ij &lt;= M)。 FJ的奶牛不太聪明，所以K_i的总和至多为100,000。 <br />
两头牛，不能直接交流，除非它们都会讲某一门语言。然而，没有共同语言的奶牛们，可以让其它的牛给他们当翻译。换言之，牛A和B可以谈话，当且仅当存在一个序列奶牛T_1，T_2，...，T_k，A和T_1都会说某一种语言，T_1和T_2也都会说某一种语言&hellip;&hellip;，并且T_k和B会说某一种语言。 <br />
农夫约翰希望他的奶牛更加团结，所以他希望任意两头牛之间可以交流。他可以买书教他的奶牛任何语言。作为一个相当节俭的农民，FJ想要购买最少的书籍，让所有他的奶牛互相可以说话。 <br />
帮助他确定： <br />
&nbsp;&nbsp;&nbsp;&nbsp;*他必须购买的书籍的最低数量 <br />
</font></p></p><hr/><h3>输入格式</h3><p><p><font size="3" face="Times New Roman">*第1行：两个用空格隔开的整数：N和M <br />
*第2.. N +1行：第i +1行描述的牛i的语言，K_i+1个空格隔开的整数：K_i L_i1 <br />
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;L_i2，...，L_I{K_i}。</font></p>
<p></p></p><hr/><h3>输出格式</h3><p><p><font size="3" face="Times New Roman">*第1行：一个整数，FJ最少需要购买的书籍数量。 <br />
</font></p>
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<pre></pre>
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<pre>
	</pre></p><hr/><h3>样例输入</h3><pre>3 3
2 3 2
1 2
1 1
</pre><hr/><h3>样例输出</h3><pre>1</pre><hr/><h3>提示</h3><p><p>给三号牛买第二本书即可</p></p><hr/><h3>题目来源</h3><p>Silver</p>
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